Hey all it's been a while since I've posted. I have an electrician telling me that in my 30x48 metal pole barn, cement floor and 12 foot side walls and sissor trusses that 4- 6 bulb T8 fixtures is enough lighting to light the place bright. This is what his supplier is telling him. I think he's way off base here and not even close. Please tell me the truth...
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6 bulb T8 fixtures
- Thread starter mothgrey
- Start date
pattenp
Well-known member
All depends on what you consider to be bright. I think you should have 8 of the 6 tube fixtures. That puts the lumens at around 110 per sqft., which I think is good. That's using 2800 lumens per tube.
Oops.. made a mistake. I misread your diamentions. With 8 6 tube fixtures it's around 93 lumens per sqft with 2800 lumen tubes. It also better to spread the light out more using more fixtures with less tubes per fixture. 93 lumens per sqft is still bright.
Oops.. made a mistake. I misread your diamentions. With 8 6 tube fixtures it's around 93 lumens per sqft with 2800 lumen tubes. It also better to spread the light out more using more fixtures with less tubes per fixture. 93 lumens per sqft is still bright.
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Chitown_hillbilly
Well-known member
I have 6 of the 4 tube HO T5 fixtures with a reflector behind them (HFA2 from Howard Lighting) in a 30x40 building and I think it's pretty bright. That also puts me at that 100 lumens/sq ft mark. Its bright enough that if I walk across the yard at night and into the building with the lights are I end up squinting a little when I walk through the door.
Charles (in GA)
Well-known member
This would be something like a Lithonia IBZ 632 WD which is a T8, 6 lamp, wide dispersion fixture.
Using the photometrics on THIS PAGE click on the "interior" link in the tools menu at the top and enter your dimensions. (click cancel when it asks you to log in)
When I put in 30x48 12 high and select 100 fc at a 2.5 ft working height, it says 12 fixtures.
These are the same fixtures I have seen in a number of Lowes stores and elsewhere. Four of them will give you enough light to keep from tripping over something, thats about it.
8 bulb fixtures (same T8 wide distribution) gives you two rows of four, eight fixtures total. You want more fixtures of less bulbs however, for more even coverage.
Charles
Using the photometrics on THIS PAGE click on the "interior" link in the tools menu at the top and enter your dimensions. (click cancel when it asks you to log in)
When I put in 30x48 12 high and select 100 fc at a 2.5 ft working height, it says 12 fixtures.
These are the same fixtures I have seen in a number of Lowes stores and elsewhere. Four of them will give you enough light to keep from tripping over something, thats about it.
8 bulb fixtures (same T8 wide distribution) gives you two rows of four, eight fixtures total. You want more fixtures of less bulbs however, for more even coverage.
Charles
2ManyProjects
Well-known member
- Joined
- Jul 18, 2013
- Messages
- 757
Hey all it's been a while since I've posted. I have an electrician telling me that in my 30x48 metal pole barn, cement floor and 12 foot side walls and sissor trusses that 4- 6 bulb T8 fixtures is enough lighting to light the place bright. This is what his supplier is telling him. I think he's way off base here and not even close. Please tell me the truth...
In terms of total light output, he's not totally out to lunch. If you're a bright-light freak, it might be a little marginal; but it's certainly not a completely unreasonable amount of lighting, particularly if you will also be adding dedicated task lighting in appropriate places (such as over your workbench).
But the problem, at least as I see it, is the FORM of that lighting. Concentrating everything into just four fixtures, in a space that large, is near-certainly going to lead to very uneven lighting -- at least unless you can mount them a LOT higher than I think you can, based on your description of the building (and note, the higher you mount a fixture, the more of its total brightness you lose by the time you get down to "working height"). I'm willing to wager heavily that if you were to take those same 24 T8 tubes, and put them into 12 two-tube fixtures spaced more-or-less evenly across the room (and possibly at a somewhat lower mounting height, if feasible), you would be much happier with the final result. If you want it to be still brighter, make that 15-18 fixtures.
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2ManyProjects
Well-known member
- Joined
- Jul 18, 2013
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In terms of total light output, he's not totally out to lunch. If you're a bright-light freak, it might be a little marginal; but it's certainly not a completely unreasonable amount of lighting, particularly if you will also be adding dedicated task lighting in appropriate places (such as over your workbench).
On second thought, and after reading some of the later comments, I think I need to amend the above. A total of 24 T8 tubes is probably not going to cut it in a space that large, no matter how you distribute it. I came to this conclusion after realizing that I'm currently planning on at least 22 (and possibly as many as 34; but that's not likely) T8 tubes in my MUCH smaller (~20 x 20) garage -- albeit, with a much lower ceiling (hence less mounting height, hence less beam spread) than you have to work with.
In my case, they will be arranged with two two-tube fixtures more-or-less centered over the parking spaces, and switched for general "walk-through" illumination. The rest will be around the perimeter of the space, using semi-continuous strips of three or four fixtures set about 1-2 feet out from both side walls and the back wall. I MAY also add some at the open end; but I'll defer that decision until I see how the above works out (I rarely have the door closed when working in the garage; so any fixtures mounted there would be largely wasted anyway).